GLOSSARY. 85 



Mi'tral. A name sometimes given to the left auriculo-vcntri- 



cular valve, because of its resemblance when closed to a 



bishop's mitre. 



Mo'bile (L. mobilis, movable). Capable of spontaneous move- 

 ment. 

 Modio'lus (L. the nave of a wheel). The conical column in 



the ear round which the cochlea turns. 

 Molar (L. mola, a mill). A back tooth or grinder. 

 Mollus'ca (L. mollis, soft). A division of the Invertebrata 



comprising the soft-bodied animals. 



Molluskl'genous sacs (mollusca; L. gero, I bear). Sacs at- 

 tached to the intestinal walls of an Echinoderm, and from 



which parasitic Mollusca are developed. 

 Mo'nad (Gr. monos, one). Any minute organism consisting 



only of a single cell. 

 Mone'ra (Gr. moneres, single, solitary). The lower of the two 



groups of the Protozoa. 

 Monocotyle'donous (Gr. monos, one; kotuledon, a cup-like 



hollow). Applied to plants having only one cotyledon or 



seed-leaf to the embryo. 

 Monodel'phia (Gr. monos, one, single; delphus, womb). A 



division of the Mammalia which includes all those animals 



in which the vagina is single. 

 Monoe'cious (Gr. monos, one ; oikos, house). Having the sexes 



united in one individual ; applied to plants having the 



male and female reproductive organs on the same plant, 



but on different stems. 

 Monotrema'ta (Gr. monos, single; trema, an aperture). A 



division of the Mammalia having a cloaca which receives 



the excretions of the urinary, genital, and alimentary canals. 

 Mons Vene'ris (L. mount of Venus). The elevation, formed of 



adipose tissue, on the fore-part of the symphisis pubis in 



the female. 

 Morphology (Gr. morphe, form ; logos, a discourse). The 



branch of Biology which deals with the structure of 



animals and plants. 

 Mor'sus dia'boli (L. devil's bite). A name sometimes applied 



to the fimbriated extremity of the Fallopian tube. 

 Mo'rula (L. diminutive of morum, a mulberry). The ovum 



when, after segmentation, it exists as an aggregation of 



nucleated cells. 

 Mosasau'ria (tnosa, not satisfactorily ascertained ; Gr. sauros, a 



lizard). A group of extinct marine Lacertilia. 



